JP2003057443A - Optically anisotropic film, optical retardation plate, circularly polarizing plate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optically anisotropic film having an excellent viewing angle and hardly generating planar failure (blurring failure). SOLUTION: An oriented film having retardation values satisfying inequalities (1) and (2) and 0.6% or less break down index is used as the optically anisotropic film. (1) 0.60<Re(450)/Re(550)<0.97 (2) 1.01<Re(650)/Re(550)<1.35.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optically anisotropic film. The present invention also relates to a retardation plate effective as a λ / 4 plate. Furthermore, the present invention also relates to a circularly polarizing plate using a λ / 4 plate. Furthermore, the present invention also relates to a liquid crystal display device using a circularly polarizing plate.

[0002]

2. Description of the Related Art A λ / 4 plate has many uses related to antireflection films and liquid crystal display devices, and has already been used in practice. However, even if it is called a λ / 4 plate, most of them have achieved λ / 4 at a certain specific wavelength. λ
If the wavelength region where / 4 can be achieved is narrow, there is a problem that the contrast of the displayed image is lowered. Japanese Patent Laid-Open No. 5-27
No. 118 and No. 5-27119 each disclose a retardation plate in which a birefringent film having a large retardation and a birefringent film having a small retardation are laminated so that their optical axes are orthogonal to each other. Is disclosed.
If the difference in retardation between the two birefringent films is λ / 4 over the entire wavelength range of visible light, the retardation plate is
Theoretically, it functions as a λ / 4 plate over the entire wavelength range of visible light.

In Japanese Patent Application Laid-Open No. 10-68816, a polymer film having a λ / 4 at a specific wavelength and a polymer film made of the same material and having a λ / 2 at the same wavelength are laminated to form a wide film. A retardation plate capable of obtaining λ / 4 in the wavelength region is disclosed. JP-A-1
Japanese Patent Laid-Open No. 0-90521 also discloses a retardation plate capable of achieving λ / 4 in a wide wavelength region by laminating two polymer films. Since each of these films is a laminated type, it requires two films and requires a laminating step, which makes it difficult to reduce the cost. Japanese Unexamined Patent Publication No. 2000-137116 discloses, as a means for solving the above problems, using an optically anisotropic film obtained by stretching a cellulose acetate film as a retardation plate.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Processing the cellulose acetate film disclosed in Japanese Patent Publication No. 00-137116 and mounting it on a liquid crystal panel,
After long-term use, it was observed that the cellulose acetate film had spot-like spots (stain defect). An object of the present invention is to provide an optically anisotropic film in which surface defects (color spot defects) hardly occur. It is also an object of the present invention to provide a retardation plate, a circularly polarizing plate and a liquid crystal display device that can realize a good viewing angle.

[0005]

Means for Solving the Problems The present invention includes the following (1) to
The optically anisotropic film (4), the retardation plate (5) below, and the circularly polarizing plate (6) below are provided. (1) An optically anisotropic film having a retardation value satisfying the following formulas (1) and (2) and having a weeping index of 0.6% or less: (1) 0.60 <Re (450) / Re (550) <
0.97 (2) 1.01 <Re (650) / Re (550) <
1.35 [wherein Re (450) is an in-plane retardation value measured at a wavelength of 450 nm; Re (550) is
Is the in-plane retardation value measured at a wavelength of 550 nm; and Re (650) is the in-plane retardation value measured at a wavelength of 650 nm].

(2) The optically anisotropic film contains a retardation increasing agent containing at least two aromatic rings.
The content of 5 to 15% by mass, and the ratio of the content of the retardation increasing agent on the front and back of the film to the content of the central portion in the film thickness direction is 3.5 times or less, respectively. Anisotropic film. (3) Refractive index nx in the in-plane slow axis direction, refractive index ny in the direction perpendicular to the in-plane slow axis, and refractive index nz in the thickness direction
Is an optically anisotropic film as described in (1), which satisfies the relationship of 1 ≦ (nx-nz) / (nx-ny) ≦ 2. (4) The optically anisotropic film according to (1), which comprises cellulose acetate having a degree of acetylation of 2.4 or more and 2.9 or less.

(5) A retardation characterized by comprising an optically anisotropic film having a retardation value satisfying the following expressions (1) to (3) and having a weeping index of 0.6% or less. Plate: (1) 0.60 <Re (450) / Re (550) <
0.97 (2) 1.01 <Re (650) / Re (550) <
1.35 (3) 100 nm <Re (550) <160 nm [wherein Re (450) is the in-plane retardation value measured at a wavelength of 450 nm; Re (550) is
Is the in-plane retardation value measured at a wavelength of 550 nm; and Re (650) is the in-plane retardation value measured at a wavelength of 650 nm]. (6) The retardation plate and the polarizing film as described in (5) above are laminated so that the angle between the in-plane slow axis of the retardation plate and the polarization axis of the polarizing film is substantially 45 °. A circularly polarizing plate characterized by having. (7) A liquid crystal display device comprising a liquid crystal cell and a polarizing plate, wherein the circularly polarizing plate described in (6) is used as the polarizing plate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a retardation-increasing agent added to an optically anisotropic film (hereinafter sometimes abbreviated as film) causes stain-like defects to be deposited on the surface of the film in the form of stains, The optical anisotropy film is improved so as to clarify the cause of the spot-like defect and prevent the spot-like defect from occurring. By controlling the surface precipitation amount of the retardation increasing agent, that is, the weeping index to be 0.6% or less, more preferably 0.5% or less, and further preferably 0.4% or less, the stain defect can be solved. . The weeping index is a value obtained by an accelerated test method for evaluating the precipitation amount of the retardation increasing agent. That is, it is a value showing the exposure to ether vapor to accelerate the surface precipitation of the retardation-increasing agent and to increase the haze accompanying this.

In order to obtain a film having such a weeping index, 0.5 to 15% by mass, and more preferably 0.5 to 15% by mass of a retardation increasing agent composed of at least two aromatic rings is contained in the optically anisotropic film. 0.7 to 12% by mass,
More preferably, the content is 0.9 to 9% by mass, and the ratio of the content of the retardation increasing agent on the front and back of the film to the content of the central portion in the film thickness direction is 3.5 times or less, and more preferably 3 It is preferably not more than twice, more preferably not more than 2.5 times. That is, the weeping property is suppressed by lowering the content of the retardation increasing agent near the surface.

Optically anisotropic film wavelength 450 nm, 5
Retardation value R measured at 50 nm and 650 nm
e (450), Re (550), Re (650) are
The ranges of the expressions (1) and (2) are preferable. 0.6 <Re (450) / Re (550) <0.97 (1) Formula 1.01 <Re (650) / Re (550) <1.35 Formula (2) More preferably (3), ( It is the range of the equation 4). 0.65 <Re (450) / Re (550) <0.92 (3) Formula 1.04 <Re (650) / Re (550) <1.30 Formula (4) More preferably (5), ( It is the range of the formula 6). 0.70 <Re (450) / Re (550) <0.87 (5) Formula 1.07 <Re (650) / Re (550) <1.25 (6) Formula Re (550) is 100 nm or more and 160 nm The following is preferable, more preferably 110 nm or more and 155 nm or less,
More preferably, it is 120 nm or more and 150 nm or less.

Further, the average value of the angles formed by the slow axis in the plane of the film and the stretching direction is within ± 5 °, more preferably within ± 4 °, and even more preferably within ± 3 °. Furthermore, the refractive index nx in the in-plane slow axis direction, the refractive index ny in the direction perpendicular to the in-plane slow axis, and the refractive index nz in the thickness direction are 1 ≦ (n
x-nz) / (nx-ny) ≦ 2, more preferably 1.
2 ≦ (nx-nz) / (nx-ny) ≦ 1.9, more preferably 1.3 ≦ (nx-nz) / (nx-ny) ≦
It is 1.8.

[Polymer] As the polymer forming the film, cellulose ester is preferable, and cellulose acetate is more preferable. Cellulose acetate is obtained by esterifying (substituting) some or all of the three OH groups possessed by cellulose with an acetate group, and the preferable degree of acetylation is 2.4 or more and 2.9 or less, and more preferably 2. It is 5 or more and 2.85 or less, and more preferably 2.6 or more and 2.8 or less. These cellulose acetates may be used by blending those having different acetylation degrees. In this case, the average acetylation degree obtained by multiplying the mixing ratio of the acetylation degrees may be within this range. The degree of polymerization (viscosity average) of cellulose acetate is 20.
0 to 700 is preferable, more preferably 250 to 550,
More preferably, it is 250 to 350. The viscosity average degree of polymerization can be measured with an Ostwald viscometer, and is calculated from the measured intrinsic viscosity [η] of cellulose acylate by the following formula. DP = [η] / Km (where DP is the viscosity average degree of polymerization, Km
Is a constant 6 × 10 ⁻⁴ ) Furthermore, as the cellulose acetate, only unused (virgin) flakes may be used, but more preferably 3% by mass or more of the film-formed cellulose acetate film scraps is used.
It is preferable to use the mixture in an amount of not more than 6% by mass, more preferably not less than 6% by mass and not more than 80% by mass, further preferably not less than 10% by mass and not more than 70% by mass.

[Retardation Raising Agent] In order to adjust the retardation value at each wavelength, it is preferable to add a retardation raising agent to the cellulose acetate film. The retardation increasing agent is polymer 10
It is preferably used in the range of 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 10 parts by mass with respect to 0 parts by mass. It is more preferable to use it, and it is most preferable to use it in the range of 0.5 to 3 parts by mass. You may use together two or more types of retardation raising agents. The retardation increasing agent preferably has a maximum absorption wavelength in the wavelength region of 230 to 360 nm. Further, the retardation increasing agent preferably has substantially no absorption in the visible region. As the retardation increasing agent, it is preferable to use a compound having at least two “aromatic rings”. This "aromatic ring" includes an aromatic heterocycle in addition to an aromatic hydrocarbon ring. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle,
A member ring, a 6-membered ring or a 7-membered ring is preferable, and a 5-membered ring or a 6-membered ring is more preferable. The aromatic heterocycle generally has the largest number of double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of the aromatic hetero ring are a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazan ring, a triazole ring, a pyran ring and a pyridine ring. , A pyridazine ring, a pyrimidine ring, a pyrazine ring and a 1,3,5-triazine ring. Specific examples of the aromatic ring include benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. preferable. The number of these aromatic rings is preferably 2 to 20, more preferably 2 to 12, and most preferably 2 to 6.

As the retardation increasing agent, any of the following (a) plate-like compound and (b) rod-like compound may be used. These may be used alone or in combination. It is more preferable to use a rod-shaped compound.

(A) Plate-like compound This compound contains two pairs of aromatic rings. The bonding relationship between these two aromatic rings is such that when (a) a condensed ring is formed, (b) a single ring is formed. It can be classified into a direct bond and a (c) bond via a linking group (a spiro bond cannot be formed because of an aromatic ring), but the bonding relationship is from (a) to
Any of (c) may be used.

Examples of the condensed ring of (a) (condensed ring of two or more aromatic rings) include indene ring, naphthalene ring, azulene ring, fluorene ring, phenanthrene ring, anthracene ring, acenaphthylene ring, biphenylene ring, Naphthacene ring, pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline Ring, isoquinoline ring,
Quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thianthrene ring included. A naphthalene ring, an azulene ring, an indole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, a benzotriazole ring and a quinoline ring are preferable.

The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two or more single bonds may combine two aromatic rings to form an aliphatic ring or a non-aromatic heterocycle between the two aromatic rings. (C)
The linking group of is also preferably bonded to carbon atoms of two aromatic rings. The linking group is an alkylene group, an alkenylene group, an alkynylene group, -CO-, -O-, -NH-,-.
It is preferably S- or a combination thereof.
Examples of linking groups composed of combinations are shown below. Note that the left-right relationship in the following examples of the linking group may be reversed.

C1: -CO-O-c2: -CO-NH-c3: -alkylene-O-c4: -NH-CO-NH-c5: -NH-CO-O-c6: -O-CO-O -C7: -O-alkylene-O- c8: -CO-alkenylene-c9: -CO-alkenylene-NH-c10: -CO-alkenylene-O- c11: -alkylene-CO-O-alkylene-O-CO.
-Alkylene-c12: -O-alkylene-CO-O-alkylene-O-
CO-alkylene-O-c13: -O-CO-alkylene-CO-O-c14: -NH-CO-alkenylene-c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent. Examples of the substituent include a halogen atom (F, C
1, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl group, alkenyl group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group , Alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic substituted sulfamoyl group, aliphatic substituted ureido group and non-aromatic An aromatic heterocyclic group is included.

The alkyl group preferably has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a straight chain alkyl group is particularly preferable.
The alkyl group may further have a substituent (eg, hydroxy, carboxy, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2
-Hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-diethylaminoethyl. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a straight chain alkenyl group is particularly preferable.
The alkenyl group may further have a substituent. Examples of alkenyl groups include vinyl, allyl and 1-hexenyl. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a straight chain alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of alkynyl groups include ethynyl, 1-butynyl and 1-hexynyl.

The number of carbon atoms of the aliphatic acyl group is 1 to 1
It is preferably 0. Examples of the aliphatic acyl group include acetyl, propanoyl and butanoyl. The number of carbon atoms of the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include acetoxy. The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (eg, an alkoxy group). Examples of alkoxy groups (including substituted alkoxy groups) include methoxy, ethoxy, butoxy and methoxyethoxy. The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl. The alkoxycarbonylamino group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonylamino group include methoxycarbonylamino and ethoxycarbonylamino.

The number of carbon atoms of the alkylthio group is 1 to 1.
It is preferably 2. Examples of the alkylthio group include methylthio, ethylthio and octylthio.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of alkylsulfonyl groups include methanesulfonyl and ethanesulfonyl. The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide. The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamide group include methanesulfonamide, butanesulfonamide and n-octanesulfonamide. The aliphatic substituted amino group preferably has 1 to 10 carbon atoms. Examples of the aliphatic substituted amino group include dimethylamino, diethylamino and 2-carboxyethylamino. The number of carbon atoms of the aliphatic-substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include methylcarbamoyl and diethylcarbamoyl. The number of carbon atoms of the aliphatic-substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include methylsulfamoyl and diethylsulfamoyl. The aliphatic substituted ureido group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted ureido group include methylureido. Examples of the non-aromatic heterocyclic group include piperidino and morpholino. The molecular weight of the retardation increasing agent is preferably 300 to 800. The retardation increasing agent is described in International Patent Application Publication No. WO00 / 65384.

(B) In the ultraviolet absorption spectrum of the rod-shaped compound solution, the maximum absorption wavelength (λ
A rod-shaped compound having a max) wavelength shorter than 250 nm can also be used as a retardation increasing agent. From the viewpoint of the function of the retardation increasing agent, the rod-shaped compound preferably has at least one aromatic ring, and more preferably has at least two aromatic rings. The rod-shaped compound preferably has a linear molecular structure. The linear molecular structure means that the rod-shaped compound has a linear molecular structure in the most thermodynamically stable structure. The thermodynamically most stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Ltd.) can be used to calculate the molecular orbital to obtain the molecular structure that minimizes the heat of formation of the compound. The linear molecular structure means that the angle of the molecular structure is 140 degrees or more in the thermodynamically most stable structure calculated as described above.

The rod-shaped compound is preferably a compound represented by the following formula (I). (I) Ar ¹ -L ¹ -Ar ^{2 In} formula (I), Ar ¹ and Ar ² are each independently an aromatic group. In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The aryl group and the substituted aryl group are more preferable than the aromatic heterocyclic group and the substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, a 6-membered ring or a 7-membered ring, more preferably a 5-membered ring or a 6-membered ring. The aromatic heterocycle generally has the largest number of double bonds. The hetero atom is preferably a nitrogen atom, an oxygen atom or a sulfur atom, more preferably a nitrogen atom or a sulfur atom. Examples of the aromatic hetero ring are a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazan ring,
It includes a triazole ring, a pyran ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, and a 1,3,5-triazine ring. As the aromatic ring of the aromatic group,
A benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable.

Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, B
r, I), hydroxyl, carboxyl, cyano, amino, alkylamino group (eg, methylamino, ethylamino, butylamino, dimethylamino), nitro, sulfo, carbamoyl, alkylcarbamoyl group (eg, N-
Methylcarbamoyl, N-ethylcarbamoyl, N, N
-Dimethylcarbamoyl), sulfamoyl, alkylsulfamoyl group (eg, N-methylsulfamoyl, N
-Ethylsulfamoyl, N, N-dimethylsulfamoyl), ureido, alkylureido group (eg, N-methylureido, N, N-dimethylureido, N, N, N ')
-Trimethylureido), an alkyl group (eg, methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, isopropyl, s-butyl, t-amyl, cyclohexyl, cyclopentyl), an alkenyl group (eg, vinyl, allyl, hexenyl). , An alkynyl group (eg, ethynyl, butynyl), an acyl group (eg, formyl, acetyl,
Butyryl, hexanoyl, lauryl), acyloxy group (eg, acetoxy, butyryloxy, hexanoyloxy, lauryloxy), alkoxy group (eg, methoxy,
Ethoxy, propoxy, butoxy, pentyloxy, heptyloxy, octyloxy), aryloxy group (eg, phenoxy), alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, heptyloxycarbonyl) ), An aryloxycarbonyl group (eg, phenoxycarbonyl), an alkoxycarbonylamino group (eg, butoxycarbonylamino,
Hexyloxycarbonylamino), an alkylthio group (eg, methylthio, ethylthio, propylthio, butylthio, pentylthio, heptylthio, octylthio),
Arylthio group (eg, phenylthio), alkylsulfonyl group (eg, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl, octylsulfonyl), amide group (eg, acetamide, butylamide group, hexylamide, lauryl) Amide) and non-aromatic heterocyclic groups (eg morpholyl, pyrazinyl).

Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom, cyano, carboxyl, hydroxyl, amino, an alkyl-substituted amino group, an acyl group, an acyloxy group, an amide group, an alkoxycarbonyl group and an alkoxy group. Groups, alkylthio groups and alkyl groups are preferred. The alkyl moiety of the alkylamino group, the alkoxycarbonyl group, the alkoxy group and the alkylthio group and the alkyl group may further have a substituent. Examples of alkyl moieties and substituents on alkyl groups include halogen atoms, hydroxyl, carboxyl, cyano, amino, alkylamino groups, nitro, sulfo, carbamoyl, alkylcarbamoyl groups, sulfamoyl,
Alkylsulfamoyl group, ureido, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group , Alkylsulfonyl groups, amide groups and non-aromatic heterocyclic groups. As the alkyl moiety and the substituent of the alkyl group, a halogen atom, hydroxyl, amino, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group and an alkoxy group are preferable.

In the formula (I), L ¹ is an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO.
And a divalent linking group selected from the group consisting of combinations thereof. The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a straight chain alkylene group is preferable to a branched alkylene group. The number of carbon atoms of the alkylene group is preferably 1 to 20, more preferably 1 to 15, and 1 to 1
0 is more preferred, 1 to 8 is still more preferred, and 1 to 6 is most preferred.

The alkenylene group and alkynylene group are
A chain structure is preferable to a cyclic structure, and a straight chain structure is more preferable to a branched chain structure. The alkenylene group and the alkynylene group each have preferably 2 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, further preferably 2 to 6 carbon atoms, and further preferably 2 to 4 carbon atoms. Most preferably, it is 2 (vinylene or ethynylene).

An example of a divalent linking group composed of a combination will be shown. L-1: -O-CO-alkylene group -CO-O- L-2: -CO-O-alkylene group -O-CO- L-3: -O-CO-alkenylene group -CO-O-L- 4: -CO-O-alkenylene group-O-CO-L-5: -O-CO-alkynylene group-CO-O-L-6: -CO-O-alkynylene group-O-CO-

In the molecular structure of the formula (I), the angle formed by Ar ¹ and Ar ² with L ¹ interposed therebetween is preferably 140 degrees or more. As the rod-shaped compound, a compound represented by the following formula (II) is more preferable. (II) Ar ¹ -L ² -X-L ³ -Ar ^{2 In} formula (II), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as Ar ¹ and Ar ² of the formula (I).

In the formula (II), L ² and L ³ are each independently a divalent linking group selected from the group consisting of alkylene groups, —O—, —CO— and combinations thereof. The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a straight chain structure rather than a branched chain structure. The alkylene group preferably has 1 to 10 carbon atoms, and 1
To 8 is more preferred, 1 to 6 is more preferred, 1 to 4 is still more preferred, and 1 or 2 (methylene or ethylene) is most preferred. L ² and L ³ are —O—CO—
Alternatively, —CO—O— is particularly preferable.

In the formula (II), X is 1,4-cyclohexylene, vinylene or ethynylene. Specific examples of the compound represented by formula (I) are shown below.

[0033]

[Chemical 1]

[0034]

[Chemical 2]

[0035]

[Chemical 3]

[0036]

[Chemical 4]

[0037]

[Chemical 5]

[0038]

[Chemical 6]

[0039]

[Chemical 7]

[0040]

[Chemical 8]

[0041]

[Chemical 9]

Specific examples (1) to (34), (41), (4)
2) has two asymmetric carbon atoms at the 1-position and 4-position of the cyclohexane ring. However, specific examples (1), (4) to
Since (34), (41) and (42) have a symmetrical meso-type molecular structure, they do not have optical isomers (optical activity), and only geometric isomers (trans type and cis type) exist. The trans type (1-trans) and cis type (1-cis) of the specific example (1) are shown below.

[0043]

[Chemical 10]

As mentioned above, the rod-shaped compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type. The specific examples (2) and (3) have optical isomers (total of 4 isomers) in addition to geometrical isomers. Regarding geometrical isomers, the trans form is also preferable to the cis form. The optical isomer is not particularly superior or inferior and may be any of D, L and racemates. In specific examples (43) to (45), the central vinylene bond has a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

The wavelength (λma) that gives the absorption maximum of the ultraviolet absorption spectrum of the solution of a typical rod-shaped compound is shown below.
x) is shown. 10-trans: 220 nm 23-trans: 230 nm 29-trans: 240 nm 41-trans: 230 nm

Two or more rod-shaped compounds may be used in combination. The rod-shaped compound can be synthesized by referring to the method described in the literature. References include Mol. Cryst. Liq. Cryst., 53, 2
29 pages (1979), 89 volumes, 93 pages (1982)
Year), 145 volumes, 111 pages (1987), 170 volumes, 4
Page 3 (1989), J. Am. Chem. Soc., 113, 1
349 pages (1991), 118 volumes, 5346 pages (19
1996), 92, 1582 (1970), J. Or.
g. Chem., 40, 420 (1975), Tetrahedr
on, Vol. 48, No. 16, page 3437 (1992). The addition amount of the retardation increasing agent is preferably 0.1 to 30% by mass of the amount of the polymer,
It is more preferably 0.5 to 20% by mass. You may use together two or more types of retardation raising agents.

[Plasticizer] A plasticizer may be added to the cellulose acetate film in order to improve the mechanical properties or the drying speed. A phosphoric acid ester or a carboxylic acid ester is used as the plasticizer. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Typical carboxylic acid esters are phthalic acid esters and citric acid esters. Examples of phthalates include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DO).
P), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalates plasticizer (DM
P, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. Since the addition amount of the plasticizer may affect the wavelength dispersion, it needs to be adjusted together with the addition amount of the retardation adjusting agent. The amount of cellulose acetate 0.1
To 25% by mass, preferably 1 to 20% by mass, more preferably 3 to 15% by mass.

[Anti-deterioration agent] To the cellulose acetate film, an anti-deterioration agent (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine) is added. Good. Regarding the deterioration preventing agent, JP-A-3-199201, JP-A-5-1907073, and JP-A-5-197070.
194789, 5-271471, and 6-1.
It is described in each publication of No. 07854. The amount of the deterioration inhibitor added is 0.01 to 1% by mass of the solution (dope) to be prepared.
Is preferable, and 0.01 to 0.2 mass% is more preferable. If the addition amount is less than 0.01% by mass, the effect of the deterioration inhibitor is hardly recognized.
If the amount added exceeds 1% by mass, bleed-out (bleeding) of the deterioration inhibitor may be observed on the film surface. Butylated hydroxytoluene (BHT) and tribenzylamine (TBA) can be mentioned as examples of particularly preferable deterioration preventing agents.

[Production of Cellulose Acetate Dope] It is preferable to produce a cellulose acetate film by a solvent casting method. In the solvent cast method, a film is manufactured using a solution (dope) in which a polymer is dissolved in an organic solvent. Organic solvents have 3 carbon atoms
It is preferable to include a solvent selected from an ether having 1 to 12 carbon atoms, a ketone having 3 to 12 carbon atoms, an ester having 3 to 12 carbon atoms, and a halogenated hydrocarbon having 1 to 6 carbon atoms. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, -O-, -CO- and -COO-) can also be used as the organic solvent. The organic solvent is
It may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. Examples of the ester having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of organic solvents having two or more types of functional groups,
Includes 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The number of carbon atoms in the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of hydrogen atoms of the halogenated hydrocarbon substituted with halogen is preferably 25 to 75 mol%, and 3
It is more preferably 0 to 70 mol%, further preferably 35 to 65 mol%, and 40 to 60
Most preferably, it is mol%. Methylene chloride is a typical halogenated hydrocarbon. You may mix and use 2 or more types of organic solvents.

The polymer solution can be prepared by a general method. The general method means treatment at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared by using the dope preparation method and apparatus in the usual solvent casting method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent. The amount of the polymer is adjusted so that the obtained solution contains 10 to 40% by mass. More preferably, the amount of polymer is from 10 to 30% by weight. The organic solvent (main solvent) may contain any of the additives described below.
The solution can be prepared by stirring the polymer and the organic solvent at room temperature (0 to 40 ° C.). The highly concentrated solution may be stirred under pressure and heat. Specifically, the polymer and the organic solvent are put in a pressure vessel and sealed, and the mixture is stirred under pressure while heating to a temperature not lower than the boiling point of the solvent at room temperature and not boiling the solvent. The heating temperature is usually 40 ° C. or higher, preferably 60 to 2
The temperature is 00 ° C, and more preferably 80 to 110 ° C.

The respective components may be roughly mixed in advance and then put in a container. Moreover, you may throw in in a container one by one. The container must be configured to allow stirring. The container can be pressurized by injecting an inert gas such as nitrogen gas. Alternatively, the increase in vapor pressure of the solvent due to heating may be used.
Alternatively, after sealing the container, each component may be added under pressure. When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. It is also possible to heat the entire container by providing a plate heater outside the container and piping to circulate the liquid. It is preferable to provide a stirring blade inside the container and use this to stir. The stirring blade is preferably long enough to reach the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the wall of the container. Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container.
The prepared dope is cooled and then taken out from the container, or after taking out, it is cooled using a heat exchanger or the like.

The solution can also be prepared by the cooling dissolution method. In the cooling dissolution method, the polymer can be dissolved even in an organic solvent which is difficult to dissolve by a usual dissolution method. Even if the solvent is capable of dissolving the polymer by the usual dissolution method, the cooling dissolution method has an effect of rapidly obtaining a uniform solution. In the cooling dissolution method, first, the polymer is gradually added to the organic solvent with stirring at room temperature. The amount of polymer is 10 to 4 in this mixture.
It is preferable to adjust the content to be 0% by mass. More preferably, the amount of polymer is from 10 to 30% by weight. Furthermore, any additives described below may be added to the mixture. Then, the mixture is -100 to-
10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, and most preferably -50 to-)
30 ° C). Cooling is done with dry ice
It can be carried out in a methanol bath (-75 ° C) or a cooled diethylene glycol solution (-30 to -20 ° C). When cooled in this way, the mixture of polymer and organic solvent solidifies. The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, 12 ° C.
Most preferably, it is not less than / minute. The higher the cooling rate, the more preferable, but 10,000 ° C./sec is the theoretical upper limit, 1000 ° C./sec is the technical upper limit, and 10
0 ° C./sec is a practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling until the final cooling temperature is reached.

Further, this is 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C.,
The polymer is dissolved in the organic solvent when heated to the most preferably 0 to 50 ° C. The temperature may be raised by leaving it at room temperature or by heating it in a warm bath. The heating rate is 4
C./minute or more is preferable, 8 DEG C./minute or more is more preferable, and 12 DEG C./minute or more is most preferable. The faster the heating rate, the better, but 100
00 ° C./sec is the theoretical upper limit, 1000 ° C./sec is the technical upper limit, and 100 ° C./sec is the practical upper limit. The heating rate is a value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating to the final heating temperature. is there. A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be judged only by visually observing the appearance of the solution. In the cooling dissolution method, it is desirable to use a closed container in order to avoid mixing of water due to dew condensation during cooling. Also, in the cooling and heating operation, when pressure is applied during cooling and pressure is reduced during heating,
The dissolution time can be shortened. In order to carry out the pressurization and depressurization, it is desirable to use a pressure resistant container.

[Film formation of cellulose acetate film]
A cellulose acetate film is produced from the prepared cellulose acetate solution (dope) by the solvent casting method. The dope before casting has a solid content of 10 to 4
It is preferable to adjust the concentration so as to be 0%. The dope (cellulose acetate solution) prepared from the dissolver (kettle) is temporarily stored in a storage kettle to remove bubbles contained in the dope or perform final preparation. The dope is sent from the dope outlet to the pressurizing die through a pressurizing quantitative gear pump that can deliver the dope with high accuracy by the number of rotations, and the dope of the casting part running endlessly from the die (slit) of the pressurizing die. Cast evenly on a support (band or drum). The surface of the drum or band is preferably mirror-finished. In the present invention, a single layer may be cast, or a plurality of two or more cellulose acetate liquids may be cast. In the case of casting a plurality of cellulose acetate solutions, a film may be prepared while casting a solution containing cellulose acetate from a plurality of casting holes provided at intervals in the traveling direction of the support while laminating the solutions. For example, the methods described in JP-A-1-122419 and JP-A-11-198285 can be applied. Further, it may be formed into a film by casting a cellulose acetate solution from two casting ports, for example, as described in JP-B-60-27562, JP-A-61-158413, and JP-A-6-134933. It can be carried out by the method described in each publication. In addition, JP-A-56
The cellulose acetate film casting method described in JP-A-162617 may be a cellulose acetate film casting method in which the flow of the high-viscosity cellulose acetate solution is wrapped with a low-viscosity cellulose acetate solution and the high- and low-viscosity cellulose acetate solutions are simultaneously extruded. Alternatively, using two casting ports, the film cast on the support by the first casting port is peeled off, and the second casting is performed on the side in contact with the surface of the support to prepare a film. Alternatively, for example, Japanese Patent Publication No.
This is the method described in Japanese Patent No. 235. The cellulose acetate solutions to be cast may be the same solution or different cellulose acetate solutions and are not particularly limited. In order to give a function to a plurality of cellulose acetate layers, a cellulose acetate solution according to the function,
It is sufficient to extrude from each casting port. It is also preferable to use these layers as functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer, etc.). The number of layers of these laminates is preferably 2 or more and 10 or less, more preferably 2 or more and 4 or less.

The present invention is characterized in that the distribution of the retardation increasing agent is adjusted in the drying process from the casting. This is because the retardation increasing agent tends to concentrate on the surface as the solvent volatilizes in the drying step, but the retardation increasing agent is slower than the speed at which it reaches the surface of the solvent. That is, in the present invention, the retardation increasing agent is prevented from precipitating in the vicinity of the surface by volatilizing the solvent before the retardation increasing agent reaches the vicinity of the surface. Such rapid drying requires that the temperature of the band or drum be 40 ° C or higher and 110 ° C.
The temperature is preferably 50 ° C. or higher and 100 ° C. or lower, more preferably 55 ° C. or higher and 90 ° C. or lower. The temperature of the drying air blown onto the band or drum is also 40 ° C. or higher and 90 ° C. or lower, more preferably 50 ° C. or higher and 85 ° C. or lower, and further preferably 55 ° C. or higher and 80 ° C. or lower. After that, the dope film (also referred to as a web) which is dry and dried is peeled off from the support at a peeling point where the band and the drum make one round. In the present invention, the residual solvent in the dope film at this time is 25% or more and 70% or less, more preferably 30% or less.
% To 60%, more preferably 35% to 50%
Peeling off is preferred below. That is, the solvent evaporates only from one surface on the band and the drum, but when stripped from this surface, the solvent evaporates from both surfaces, so that the solvent can be dried at a higher speed. Therefore, the present invention is characterized by peeling and drying in such a state of high volatile content, whereas the peeling is usually performed at 20% or less. Since such a web containing a large amount of residual solvent is not stiff and is difficult to convey, rolls cannot be conveyed, and both ends of the web are sandwiched by clips, and the web is conveyed while being held by a tenter while drying. At this time, the air volume of the dry air blown from the lower side of the web is 10 with respect to the air volume of the dry air from the upper side.
% Or more and 60% or less, more preferably 20% or more and 50% or less, still more preferably 25% or more and 45% or less, and blow out. As a result, it is possible to prevent the web from hanging down due to its own weight, and it is possible to carry out the web transport of the high residual solvent as in the present invention. When the residual solvent becomes 5% or less by this, it is conveyed by the roll group of the drying device, the drying is completed, and it is wound into a predetermined length by the winding machine. The thickness of the film after casting is 80 to 300 μm
Is preferable, and more preferably 90 to 250 μm.
m, more preferably 100 to 200 μm. Furthermore, it is also preferable to coat and provide a functional layer (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer, etc.) on at least one side of these films. Further, a mat layer containing a matting agent and a polymer may be provided on one side or both sides in order to improve handleability during production. As the matting agent and the polymer, the materials described in JP-A-10-44327 can be preferably used.

[Stretching of cellulose acetate film]
The cellulose acetate film can be stretched to achieve the optical properties (retardation, etc.) and mechanical properties (elongation at break, breaking strength, folding endurance) of the present invention.
The present invention is characterized by improving this stretching method. Stretching may be carried out in any of the longitudinal and lateral directions,
You may combine these. Of these, longitudinal or lateral uniaxial stretching is preferred, and longitudinal uniaxial stretching is more preferred. A preferred draw ratio is 1.1 times or more.
It is 8 times or less, more preferably 1.15 times or more and 1.75 times or less, and further preferably 1.2 times or more and 1.7 times or less. Stretching may be performed in one stage or in multiple stages.
When performing in multiple stages, the product of each draw ratio should be within this range. Stretching speed is 50% / min or more 1000
% / Min or less, more preferably 80% / min or more and 800% /
Min or less, more preferably 100% / min or more and 700% /
It is less than a minute. A preferred stretching temperature is 115 ° C or higher and 160
C. or lower, more preferably 120.degree. C. or higher and 155.degree. C. or lower, and still more preferably 125.degree. C. or higher and 150.degree. C. or lower. Stretching can be achieved by using two pairs of nip rolls and increasing the speed on the outlet side from the speed on the nip rolls on the inlet side. At this time, it is preferable that the span length between the nip rolls is 2 to 8 times the film width before stretching. The film width before stretching is preferably 30 cm or more and 2 m or less, and more preferably 50 cm or more and 1.5 m or less.

[Surface Treatment of Optically Anisotropic Film] The optically anisotropic film is preferably surface-treated. Specific methods include corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment and ultraviolet irradiation treatment. Further, it is also preferable to provide an undercoat layer as described in JP-A-7-333433. Surface energy is 55mN by these surface treatments
/ M or more, preferably 60 mN / m or more 75
It is more preferably mN / m or less. In the case of the cellulose acetate film subjected to these treatments, it is particularly preferable to carry out acid treatment or alkali treatment, that is, saponification treatment. Among these treatments, from the viewpoint of adhesion, it is particularly preferable to carry out acid treatment or alkali treatment, that is, saponification treatment of cellulose acetate.
Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution, and the normal concentration of hydroxide ion is preferably 0.1N to 3.0N, and 0.5N.
To 2.0 N is more preferable. The temperature of the alkaline solution is preferably room temperature to 90 ° C, more preferably 40 ° C to 70 ° C. Such saponification may be carried out by either a dipping method (the film is dipped in an acid or alkaline solution) or a coating method (the surface of the film is coated with an acid or an alkaline solution). After this, it is preferable to neutralize and wash with a dipping method or a coating method.

[Circular Polarizing Plate] The optical anisotropic film of the present invention and the polarizing plate are prepared so that the angle between the in-plane slow axis of the optically anisotropic film of the present invention and the polarizing axis of the polarizing plate is substantially the same. A circularly polarizing plate can be obtained by laminating the substrates at 45 °. The polarizing plate means a polarizing film sandwiched between transparent protective films.
Substantially 45 ° means 40 to 50 °. The angle between the average direction of the in-plane slow axis of the optically anisotropic film of the present invention and the polarization axis of the polarizing film is 41 to 49.
The angle is preferably 40 °, more preferably 42 to 48 °, further preferably 43 to 47 °, and most preferably 44 to 46 °. The optically anisotropic film of the present invention and the polarizing film are laminated so that the angle between the in-plane slow axis of the optically anisotropic film of the present invention and the polarizing axis of the polarizing film is substantially 45 °. A circularly polarizing plate can also be obtained by this. The polarizing film includes an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film. The iodine type polarizing film and the dye type polarizing film are generally manufactured using a polyvinyl alcohol type film. The polarization axis of the polarizing film corresponds to the direction perpendicular to the stretching direction of the film. A transparent protective film is preferably provided on the surface of the polarizing film opposite to the optically anisotropic film of the present invention.

[Reflective Liquid Crystal Display Element] The reflective liquid crystal display device of the present invention comprises, in order from the bottom, a lower substrate, a reflective electrode, a lower alignment film, a liquid crystal layer, an upper alignment film, a transparent electrode, an upper substrate, and the present invention. It consists of an optically anisotropic film and a polarizing film. The angle between the in-plane slow axis of the optically anisotropic stretched film of the present invention and the polarization axis of the polarizing film is substantially 45 °. The lower substrate and the reflective electrode form a reflector. The lower alignment film to the upper alignment film form a liquid crystal cell. The optically anisotropic film of the present invention can be arranged at any position between the reflection plate and the polarizing film. In the case of color display, a color filter layer is further provided. The color filter layer is preferably provided between the reflective electrode and the lower alignment film or between the upper alignment film and the transparent electrode. A transparent electrode may be used instead of the reflective electrode, and another reflective plate may be attached. A metal plate is preferable as the reflector used in combination with the transparent electrode. If the surface of the reflector is smooth, only the specular reflection component may be reflected and the viewing angle may be narrowed. Therefore, it is preferable to introduce an uneven structure (described in Japanese Patent No. 275620) on the surface of the reflection plate. When the surface of the reflection plate is flat (instead of introducing an uneven structure on the surface), a light diffusion film may be attached to one side (cell side or outside) of the polarizing film.

The liquid crystal cell is TN (twisted nematic)
Type, STN (Supper Twisted Nematic) type or HAN
A (Hybrid Aligned Nematic) type is preferable.
The twist angle of the TN type liquid crystal cell is preferably 40 to 100 °, more preferably 50 to 90 °, and most preferably 60 to 80 °.
The product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is preferably 0.1 to 0.5 μm, and 0.2 to 0.4 μm. It is more preferable that there is. The twist angle of the STN type liquid crystal cell is 180
It is preferably from 360 to 360 °, and 220 to 270
More preferably, The value (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is preferably 0.3 to 1.2 μm,
More preferably, it is 5 to 1.0 μm. HAN
In the type liquid crystal cell, the liquid crystal is substantially vertically aligned on one substrate, and the pretilt angle on the other substrate is 0 to 4.
It is preferably 5 °. Refractive index anisotropy of liquid crystal layer (Δ
The value of the product (Δnd) of n) and the thickness (d) of the liquid crystal layer is
The thickness is preferably 0.1 to 1.0 μm, more preferably 0.3 to 0.8 μm. The substrate on the side of vertically aligning the liquid crystal may be the substrate on the reflection plate side or the substrate on the transparent electrode side. The polarizing film includes an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film. The iodine type polarizing film and the dye type polarizing film are generally manufactured using a polyvinyl alcohol type film. The polarization axis of the polarizing film corresponds to the direction perpendicular to the stretching direction of the film. The reflective liquid crystal display device can be used in a normally white mode in which bright display is performed when the applied voltage is low and dark display when the applied voltage is high, or in a normally black mode in which dark display is applied when the applied voltage is low and bright display is applied when the applied voltage is high. . Normally white mode is preferred.

[Guest-Host Reflective Liquid Crystal Display Element] The guest-host reflective liquid crystal display element includes a lower substrate, an organic interlayer insulating film, a metal reflector, an optically anisotropic film of the present invention, a lower transparent electrode, a lower alignment film, The liquid crystal layer, the upper alignment film, the upper transparent electrode, the light diffusing plate, the upper substrate, and the antireflection layer are laminated in this order. The lower substrate and the upper substrate are made of glass plate or plastic film. A TFT is attached between the lower substrate and the organic interlayer insulating film. The liquid crystal layer is composed of a mixture of liquid crystal and dichroic dye. The liquid crystal layer is
It is obtained by injecting a mixture of liquid crystal and dichroic dye into the cell gap formed by the spacer. Instead of providing the light diffusing plate, the metal diffusing plate may be provided with an uneven surface to impart a light diffusing function to the metal reflecting plate. The antireflection layer preferably has an antiglare function in addition to the antireflection function.

The guest-host reflective liquid crystal display device includes a lower substrate, an organic interlayer insulating film, a cholesteric color reflector, the optically anisotropic film of the present invention, a lower transparent electrode, a lower alignment film, a liquid crystal layer, an upper alignment film and an upper alignment film. The transparent electrode, the upper substrate, and the antireflection layer are laminated in this order. The lower substrate and the upper substrate are made of glass plate or plastic film. A TFT is attached between the lower substrate and the organic interlayer insulating film. The optically anisotropic film may also function as a light diffusing plate. The liquid crystal layer is composed of a mixture of liquid crystal and dichroic dye. The liquid crystal layer is obtained by injecting a mixture of liquid crystal and dichroic dye into the cell gap formed by the spacer. A black matrix is attached between the upper transparent electrode and the upper substrate. The antireflection layer preferably has an antiglare function in addition to the antireflection function.

The optically anisotropic film according to the present invention can be used as an optically anisotropic film of a guest-host reflective liquid crystal display device. A guest-host reflective liquid crystal display device having an optically anisotropic film is disclosed in JP-A-6-2223.
No. 50, No. 8-36174, No. 10-268300.
No. 10-292175 and No. 10-293301.
No. 10-311976 and No. 10-319442.
No. 10-325953, No. 10-333138
And each publication of the same No. 11-38410.
The optically anisotropic film according to the present invention can also be used for the guest-host reflective liquid crystal display device described in the above publications.

[Film Measuring Method] 1) Weeping Index Samples are cut into 5 cm squares and conditioned at 25 ° C. and 60% RH for 3 hours or more. Diethyl ether is put into a glass bottle having a diameter of 3 cm and a height of 5 cm so that the liquid surface height becomes 5 mm, and then the lid is covered and sufficiently stirred to fill the vapor in the bottle. The lid of the glass bottle is opened, one side and the other side of the sample film are placed on the mouth of the bottle, a 5 cm square glass plate is placed on this, and a load of 50 g is placed. This at 25 ℃
And leave for 20 minutes and expose to ether vapor. After 20 minutes, the sample film is taken out and immediately measured for haze. The difference between this value and the haze of the sample film before aeration with ether is determined. This measurement is performed on both sides of the film, and the larger value is used as the weeping index.

2) Ratio of the content of the retardation increasing agent on the front and back of the film to the content of the central portion of the film in the thickness direction of the film. The sample film was fixed to the sample stage of the microtome, and the angle of the blade was inclined at 20 °. Direction to a thickness of 2 μm. As a result, the thickness is increased by about 3 times. Place this on a silicon wafer (one with no acid value film formed on the surface) and use a microscopic IR spectroscope (2
A rectangular aperture of 0 μm × 100 μm) is measured stepwise by 20 μm from one end (where it was the film surface) (measured so that the side of the aperture of 100 μm is parallel to the film surface). The IR measurement was integrated 200 times, and the silicon wafer right next to the sample was measured and subtracted as the background. 903 ± 3 as IR peak of cellulose acetate
Attention was paid to the peak appearing at cm ^-1 . The baseline between the valleys on both sides was drawn, and the absorbance of this peak was determined (this is designated as Aa). Furthermore, I of retardation increasing agent
As the R peak, the strongest peak among the peaks that do not overlap with the IR peak of cellulose acetate was determined, and the peak height (absorbance) based on the valley connecting both sides of this peak was determined (this is referred to as Ab). ). Ab / Aa to T
And Measured value (Tc) at the two points in the central part, the average value (Tb) of the two points, the outermost point on one side (the surface that was in contact with the band and the drum during film formation) and the inside point (Tb), opposite Divide the average value (Ta) of T at the two points of the outermost point on the surface (the surface on the side opposite to the band and the drum during film formation) and the innermost point. This was defined as the ratio of the content of the retardation increasing agent on the front and back sides of the film to the content of the central portion in the film thickness direction. The back side refers to the side that was in contact with the band or drum when it was cast on the band or drum, and the front side refers to the surface that was in contact with air.

3) Measurement of Retardation and Refractive Index The prepared cellulose acetate film (retardation plate) was measured by using an ellipsometer (M-150, manufactured by JASCO Corporation) at wavelengths of 450 nm, 550 nm and 650 nm. The foundation value was measured.
In addition, from the refractive index measurement with an Abbe refractometer and the angle dependence of the retardation, the refractive index nx in the in-plane slow axis direction at a wavelength of 550 nm and the refractive index in the direction perpendicular to the in-plane slow axis. The ny and the refractive index nz in the thickness direction were obtained, and the value of (nx-nz) / (nx-ny) was calculated.

4) Degree of acetylation 13C-NMR spectrum was measured by the method described in Polymer Journal 17. 1065-1069 (1985).

[0069]

[Example] [Example 1] 1. Preparation of Retardation Plate (Cellulose Acetate Stretched Film) (1) Composition As shown in Table 1, a cellulose acetate dope (high concentration solution) was prepared by selecting from the following two compositions.
As the retardation increasing agent, the following (1) was used as the plate-like compound shown in Table 1, and the following (2) was used as the rod-like compound. The addition amount is shown in Table 1.

[0070]

[Chemical 11]

[0071]

[Chemical 12]

[0072] (A) Methylene chloride (MC) system     120 parts by weight of cellulose acetate (degree of acetylation is shown in Table 1)     Triphenyl phosphate 9.36 parts by mass     Biphenyl diphenyl phosphate 4.68 parts by mass     Methylene chloride 704 parts by mass     Methanol 61.2 parts by mass (B) Methyl acetate (MA) system   For single layer     118 parts by mass of cellulose acetate (degree of acetylation is shown in Table 1)     Triphenyl phosphate 9.19 parts by mass     Biphenyl diphenyl phosphate 4.60 parts by mass     2.36 parts by mass of tribenzylamine     Methyl acetate 530 parts by mass     Ethanol 99.4 parts by mass     Butanol 33.1 parts by mass

(2) Dissolution These were selected from the following two dissolution methods and carried out by the method shown in Table 1. (A) Normal temperature dissolution (described as "normal temperature" in the column of dissolution method in Table 1) The compound described in Table 1 is gradually added to a solvent with good stirring, and at room temperature (25 ° C) for 3 hours. It was left to swell.
The resulting swollen mixture was dissolved in a mixing tank with a reflux condenser at 50 ° C. with stirring. (B) Cooling dissolution (described as “cooling” in the column of dissolution method in Table 1) Gradually add the compound described in Table 1 to the solvent while stirring well, and at room temperature (25 ° C.) for 3 hours. It was left to swell.
While slowly stirring the obtained swelling mixture, -8 ° C /
Cool to -30 ° C in minutes, then cool to the temperature shown in Table 1 and after 6 hours, start stirring the contents at a stage where the temperature has risen at + 8 ° C / min and the sol formation of the contents has progressed to some extent. did. The dope was obtained by heating to 50 ° C. (C) High-pressure high-temperature dissolution (described as "high temperature" in the column of dissolution method in Table 1) Gradually add the cellulose acylate described in Table 1 to a solvent while stirring well, and bring to room temperature (25 ° C). And allowed to swell for 3 hours. The obtained swelling mixture was placed in a stainless steel closed container having a double structure. High-pressure steam is passed through the jacket on the outside of the container to heat it at + 8 ° C / min to 1 MPa.
Below, the temperature shown in Table 1 was maintained for 5 minutes. After that, water at 50 ° C. was passed through the outer jacket and cooled to 50 ° C. at −8 ° C./min to obtain a dope.

[0074]

[Table 1]

(3) Film formation Film formation was carried out by selecting from the following two methods and listed in Table 1. (A) Single-layer film formation: The solution (dope) obtained by the above method was filtered with a filter paper (No. 244, manufactured by Azumi Filter Paper Co., Ltd.) and a filter cloth made of flannel, and then a single-layer film was formed with a quantitative gear pump. After the liquid was sent to the pressure die, it was simultaneously discharged onto the metal support (band) and cast. (B) Laminated film formation: Using a three-layer co-casting die, the dope having the above composition from the inner layer and the dope diluted with the solvent amount increased to 10% on both sides are simultaneously discharged onto the metal support to form a multilayer flow. Delayed Thickness ratio (thickness of inner layer: thickness of each surface layer)
Is set to 8: 1. The temperature of the band and the temperature of the air blown on the band are shown in Table 1. This is the first
After reaching the residual solvent amount shown in the table, it was peeled from the band, conveyed while gripping it with a tenter, and dried. At this time, the dry air having the temperature shown in Table 1 was sent from the upper surface and the lower surface of the film, but the air volume ratio (upper air volume / lower air volume) described in Table 1 was set. After this, these both ends 15cm
Trimming each, knurling (height adjustment) with a height of 50 μm and a width of 1 cm at both ends, width 1.5 m, length 30
An unstretched cellulose acetate film of 00 m was obtained.
The cellulose acetate film scraps trimmed here are crushed and then mixed with virgin cellulose acetate and reused (30% by mass of the total cellulose acetate is mixed).

(4) Stretching (Preparation of Optically Anisotropic Film λ / 4 Plate) An unstretched cellulose acetate film was fed out from a delivery installed outside the thermostatic chamber, and the thermostatic chamber was set at the temperature shown in Table 1. Send it in. Hard-chrome-coated stainless steel roll with a diameter of 15 cm and a diameter of 5 cm
2 pairs of the rubber-coated nip rolls were installed at a distance between roll centers of 3 times the film width before stretching, and MD stretching was performed at the magnification shown in Table 1. After this, send out from the constant temperature bath,
After cooling to room temperature, it was wound up.

(5) Evaluation The weeping property and the optical property were evaluated according to the above method, and the results are shown in Table 2. Further, the ratio of the content of the retardation increasing agent on the front and back sides of the film to the content of the central portion in the film thickness direction was measured according to the above method. In addition, the stain failure was measured. The results are shown in Table 2. Blemish failure appears after long-term storage. As a method of simulating this, after 100 hours at 60 ° C. and 80% RH, a spotted area is visually marked, and this area and total area are marked. The ratio was calculated. The allowable range is 3% or less. In the present invention, this failure hardly occurred and was good.

2. Preparation of circularly polarizing plate The transparent protective film, the polarizing film and the optically anisotropic film produced by the above method were cut into a diagonal of 15 inches and laminated in this order to obtain a circularly polarizing plate. The angle between the slow axis of the optically anisotropic film and the polarization axis of the polarizing film was adjusted to 45 °. This is mounted on a reflective liquid crystal panel, and a measuring instrument (EZ Contrast 160D, E
The viewing angle characteristics were measured using LDIM. The results are shown in Table 2. The stain failure was also measured according to the above method and is shown in Table 2. In the present invention, this failure hardly occurred and was good. Further, when the circularly polarizing plate of the present invention is used, a wide viewing angle can be obtained.

[0079]

[Table 2]

3. Preparation of reflective liquid crystal display element A glass substrate provided with an ITO transparent electrode and a glass substrate provided with an aluminum reflective electrode having fine irregularities were prepared. A polyimide alignment film (SE-7992, manufactured by Nissan Chemical Industries, Ltd.) was formed on each of the two glass substrates on the electrode side, and a rubbing treatment was performed. The two substrates were stacked with the alignment films facing each other through a spacer of 2.5 μm. The orientation of the substrate was adjusted so that the rubbing directions of the two alignment films intersect at an angle of 117 °. After this, as in the above, as a simulation method, 60 ° C. 80% RH
For 100 hours. A liquid crystal (M
LC-6252, manufactured by Merck & Co., Inc.) was injected to form a liquid crystal layer. Thus, a TN type liquid crystal cell having a twist angle of 63 ° and a value of Δnd of 198 nm was produced. The circularly polarizing plate produced by the above method was attached to the side of the glass substrate provided with the ITO transparent electrode via an adhesive. On top of that, a protective film whose surface was AR-treated was attached. A rectangular wave voltage of 1 kHz was applied to the produced reflective liquid crystal display device. When visually evaluated with a white display of 1.5 V and a black display of 4.5 V, it was confirmed in the present invention that there was no tint in both white display and black display, and that neutral gray was displayed. . Further white display, 20
The area having a square shape in cm cm was measured by the same method as above, and the results are shown in Table 2. The allowable range is 3% or less, but it hardly occurs in the present invention,
It was good. Next, a measuring machine (EZcontrast160D, El
The contrast ratio of the reflection luminance was measured by using Dim), and when the present invention was carried out, the contrast ratio from the front was 23 or more, and the viewing angle at which the contrast ratio was 3 is shown in Table 2. In the present invention, a good viewing angle was shown.

4. Preparation of guest-host reflective liquid crystal display device A solution of a vertical alignment film-forming polymer (LQ-1800, manufactured by Hitachi Chemical DuPont Micro Systems) was coated on a glass substrate provided with an ITO transparent electrode, dried and rubbed. Processed. On the glass substrate on which aluminum is vapor-deposited as a reflector, the above-mentioned optically anisotropic film (λ /
4 plates) were attached with an adhesive. This λ / 4 plate was aged in the same manner as above at 60 ° C. and 80% RH for 100 hours. A SiO layer was provided on the λ / 4 plate by sputtering, and an ITO transparent electrode was provided thereon. A polymer for vertical alignment film (L
A solution of Q-1800, manufactured by Hitachi Chemical DuPont Micro Systems Co., Ltd.) was applied, dried, and then subjected to rubbing treatment in the direction of 45 ° from the slow axis direction of the optically anisotropic film.
Two glass substrates were superposed with the alignment films facing each other through a 7.6 μm spacer. The orientation of the substrate was adjusted so that the rubbing directions of the alignment film were anti-parallel.
2.0 mass% of dichroic dye (NKX-1366, manufactured by Nippon Senshoku Co., Ltd.) and liquid crystal (ZLI-2806;
A mixture with 98.0% by mass of Merck Ltd. was injected by a vacuum injection method to form a liquid crystal layer. Between the ITO electrodes of the guest-host reflective liquid crystal display device produced by the present invention, 1 k
A square wave voltage of Hz was applied. In the present invention, the transmittances at 1 V for white display and 10 V for black display are 65% and 6%, respectively.
The transmittance ratio (contrast ratio) between white display and black display is
It was 11: 1, and the viewing angle at which a contrast ratio of 2: 1 was obtained at the top, bottom, left and right was 120 ° or more at both the top, bottom, left and right, and was good. Further, the spotted area was measured in the same manner as the above-mentioned method, but in all cases where the present invention was implemented, it was 2% or less, whereas in Comparative Examples, it was more than 5%. . The transmittance was measured while further increasing and decreasing the voltage, but no hysteresis was observed in the transmittance-voltage curve.

[0082]

According to the present invention, it is possible to provide an optically anisotropic film having a good viewing angle and less likely to cause a planar defect (stain defect).

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H049 BA02 BA03 BA07 BA26 BA27                       BA42 BB03 BB43 BB49 BC03                       BC14 BC22                 2H091 FA08X FA08Z FA11X FA11Z                       FB02 FC07 HA06 HA07 HA08                       HA10 KA01 KA02 LA17 LA19

Claims (7)

[Claims] 1. An optically anisotropic film having a retardation value satisfying the following formulas (1) and (2) and having a weeping index of 0.6% or less: (1) 0 .60 <Re (450) / Re (550) <
0.97 (2) 1.01 <Re (650) / Re (550) <
1.35 [wherein Re (450) is an in-plane retardation value measured at a wavelength of 450 nm; Re (550) is
Is the in-plane retardation value measured at a wavelength of 550 nm; and Re (650) is the in-plane retardation value measured at a wavelength of 650 nm]. 2. An optically anisotropic film containing 0.5 to 15% by mass of a retardation increasing agent composed of at least two aromatic rings, the retardation increasing agent being contained in the front and back sides of the film. The optically anisotropic film according to claim 1, wherein the ratio to the content of the central portion in the thickness direction is 3.5 times or less. 3. A refractive index nx in the in-plane slow axis direction, a refractive index ny in a direction perpendicular to the in-plane slow axis, and a refractive index nz in the thickness direction are 1 ≦ (nx−nz) / (nx The optically anisotropic film according to claim 1, wherein the relationship of −ny) ≦ 2 is satisfied. 4. The optically anisotropic film according to claim 1, which is made of cellulose acetate having a degree of acetylation of 2.4 or more and 2.9 or less. 5. A retardation plate comprising an optically anisotropic film having a retardation value satisfying the following formulas (1) to (3) and having a weeping index of 0.6% or less. : (1) 0.60 <Re (450) / Re (550) <
0.97 (2) 1.01 <Re (650) / Re (550) <
1.35 (3) 100 nm <Re (550) <160 nm [wherein Re (450) is the in-plane retardation value measured at a wavelength of 450 nm; Re (550) is
Is the in-plane retardation value measured at a wavelength of 550 nm; and Re (650) is the in-plane retardation value measured at a wavelength of 650 nm]. 6. The retardation plate and the polarizing film according to claim 5 are laminated so that an angle between the in-plane slow axis of the retardation plate and the polarizing axis of the polarizing film is substantially 45 °. A circularly polarizing plate characterized by being formed. 7. A liquid crystal display device comprising a liquid crystal cell and a polarizing plate, wherein the circularly polarizing plate according to claim 6 is used as the polarizing plate.